The present invention relates to a rubber composition and a tire using the rubber composition as the tread. More specifically, the present invention relates to a rubber composition, which can prevent a rise in rubber hardness over time and maintain good snow and ice performance over a long period of time, and a tire which uses the rubber composition as a tire tread.
In snow tire development, a tire, which can be stably used over a long period on snow and ice in wintertime, is in demand. For example, known is the technical art of maintaining low rolling resistance and wet skid resistance while improving traction and braking performance on snow and ice surfaces, by compounding rape seed oil as a softening agent to a rubber composition containing styrene-butadiene rubber (SBR) as a main component (JP-A-8-302077). However, in a rubber composition containing SBR as a main component, because tan δ peak temperature Tg becomes higher than −50° C. and hardness at a low temperature rises, sufficient performance on snow and ice could not be obtained.
A rubber composition obtained by compounding palm oil in the rubber component comprising natural rubber and butadiene rubber is also known (JP-A-58-74731). However, in a tire made from a rubber composition compounded with palm oil, rubber hardness at a low temperature became high and performance on snow and ice could not be maintained over a long period of time.
As stated above, the technical art of maintaining performance on snow and ice over a long period is still not quite satisfactory.